The UN Secretary General Ban Ki-moon has welcomed a US-backed climate deal in Copenhagen as an "essential beginning".He was speaking after delegates passed a motion recognising the agreement, which the US reached with key nations including China.
But Mr Ban said the agreement must be made legally binding next year.
Earlier, the meeting failed to secure unanimous support, amid opposition from some developing nations.
Several South American countries, such as Nicaragua and Venezuela, were among a group saying the agreement had not been reached through proper process.
Mr Ban told journalists: "Finally, we sealed the deal."
But he added: "We must transform this into a legally binding treaty next year.
"The importance will only be recognised when it's codified into international law."
Delegates at the climate summit had been battling through the night to prevent the talks ending without reaching a final deal.
Earlier, a US-led group of five nations - including China - tabled a last-minute proposal that President Barack Obama called a "meaningful agreement".
However, it had been rejected by a few developing nations which felt it failed to deliver the actions needed to halt dangerous climate change.
The majority of nations had been urging the Danish hosts to adopt the deal.
"The conference decides to take note of the Copenhagen Accord of December 18, 2009," the chairman of the plenary session of the UN Framework Convention on Climate Change (UNFCCC) declared on Saturday morning, swiftly banging down his gavel.
To be accepted as an official UN agreement, the deal needs to be endorsed by all 193 nations at the talks.
On Friday evening, the US, China, India, Brazil and South Africa reached a last-minute agreement on a number of issues, such as a recognition to limit temperature rises to less than 2C (3.6F).
However, a number of developing nations were angered by the draft proposals.
BBC environment correspondent Richard Black said the language in this text showed 2C was not a formal target, just that the group "recognises the scientific view that" the temperature increase should be held below this figure.
The five-nation proposal had promised to deliver $30bn (£18.5bn) of aid for developing nations over the next three years, and outlined a goal of providing $100bn a year by 2020 to help poor countries cope with the impacts of climate change.
The agreement also included a method for verifying industrialised nations' reduction of emissions. The US had insisted that China dropped its resistance to this measure.
During the two-week gathering, small island nations and vulnerable coastal countries had been calling for a binding agreement that would limit emissions to a level that would prevent temperatures rising more than 1.5C (2.7F) above pre-industrial levels.
The main opposition to the five-nation accord had come from the ALBA bloc of Latin American countries to which Nicaragua and Venezuela belong, along with Cuba, Ecuador and Bolivia.
But the African Union appeared to back the deal, along with most of the small island developing states.
